1. Field of the Invention
This invention generally relates to a bicycle hub gearbox for a multi-speed hub for a bicycle. More specifically, the present invention relates to a bicycle hub gearbox with at least a pair of planetary gear mechanisms.
2. Background Information
Bicycling is becoming an increasingly more popular form of recreation as well as a means of transportation. Moreover, bicycling has become a very popular competitive sport for both amateurs and professionals. Whether the bicycle is used for recreation, transportation or competition, the bicycle industry is constantly improving the various components of the bicycle. One component that has been extensively redesigned is the bicycle drive train.
Many bicycle hub assemblies include an internal power transmission mechanism having two or more power transmission paths, where each path is defined by unique gear combinations through which torque is transmitted. For example, a bicycle hub gearbox for a multi-speed hub with two planetary gear mechanisms is disclosed in document German Patent Publication No. 41 42 867 A1. The arrangement, as described in this publication, substantially includes a fixed shaft, a drive member and a hub sleeve, as well as a mechanism for transmitting the driving torque from the drive member to the hub sleeve. The transfer mechanism includes particularly a first planetary gear mechanism and a second planetary gear mechanism, which is arranged between the first planetary gear mechanism and the drive member, as well as one-way clutches and one-way sun gear clutches, wherein the planetary gear mechanisms are controlled in such a manner that the driving torque can be transmitted in different gear ratios. The actuation of the clutches, which work on the sun gears only in one direction, takes place through position-related connections of projections, which are formed at the fixed shaft, relative to the actuation elements, which are arranged at a movable shifting element at circumferential surfaces of the fixed shaft. Although the bicycle gearing according to this document functions by itself, it has disadvantages nonetheless. For example, when shifting the gears, undesirable noise can be generated and the rider can feel uncomfortable and unpleasant jerks. Moreover, the construction requires a relatively large dimension in the radial direction.
In view of the above, it will be apparent to those skilled in the art from this disclosure that there exists a need for an improved gearing mechanism. This invention addresses this need in the art as well as other needs, which will become apparent to those skilled in the art from this disclosure.